Migration failure caused by unsupported ciphers and MACs that are configured for OpenSSH - Server Migration Center

This topic describes the cause of the "OpenSSH configured to use removed ciphers" error message that is reported when you use Server Migration Center (SMC) to migrate an operating system. This topic also describes how to resolve the error.

Problem description

During the migration of an operating system, the "OpenSSH configured to use removed ciphers" error message is reported.

Cause

The OpenSSH configuration file /etc/ssh/sshd_config contains ciphers or message authentication codes (MAC) that are insecure or not recommended. This may cause operating system migration jobs to fail.

Solution

Connect to the Elastic Compute Service (ECS) instance whose operating system you want to migrate. For more information, see Connect to a Linux instance by using a password or key.
Modify the configuration file of OpenSSH.
1. Run the following command to modify the /etc/ssh/sshd_config configuration file:
```
vim /etc/ssh/sshd_config
```
2. Press the I key to enter the insert mode.
3. Remove the following ciphers that are no longer supported from the Ciphers configuration line: blowfish-cbc, cast128-cbc, arcfour, arcfour128, and arcfour256. Alternatively, comment out the Ciphers-related configuration lines.
4. Remove the following MAC algorithm that is no longer supported from the MACs configuration line: hmac-ripemd160. Alternatively, comment out the MAC-related configuration lines.
5. Press the ESC key to exit the insert mode. Enter :wq and press the Enter key to save and close the file.
After the error is resolved, run the SMC client and retry the migration job. For more information, see Run the SMC client.